The present invention relates to a method for compression of a telephone number database in a telecommunications system, and to a telecommunications system in which this method is used.
In the field of telecommunications, the aim is to set up a communications link as far as possible via the cheapest connecting path. The charges to be paid for a call in this case depend, as a rule, on the distance to the destination subscriber and the time for which the corresponding connecting path is used. In particular, destination-dependent tariff zones may be provided, which are associated with different distances to the destination subscriber being called. For lowest cost routing in telephone systems or telephone networks in countries with such destination-dependent tariff zones, it is thus necessary to store in the respective telephone system the destinations which can be accessed from the respective telephone system, with their destination code numbers, which are called xe2x80x9carea codesxe2x80x9d. Whenever a call is set up, the system controller in the corresponding telephone system searches through the entire set of these destination code numbers in order to make it possible to decide the connecting path via which the call should be routed, for cost reasons.
For reasons linked to utilization of the system controller or of the processors which act as the system controller in the respective telephone system, it is advantageous if the number of stored destination code numbers is kept as small as possible. On the other hand, it is advantageous for least cost routing (LCR) if as great a number of different connecting paths as possible can be considered when determining the connecting path. For which reason, on the other hand, it is necessary to store and control as great a number of local networks and corresponding destination code numbers as possible. In Germany, for example, there are more than 5100 different local networks, with corresponding destination code numbers (area codes) designating the respective local network.
In known telecommunications systems, attempts have already been made to consider, as far as possible, all the available destination code numbers. The range of destination code numbers to be controlled was combined only if a specific maximum number of destination code numbers was specified, for storage reasons in the respective telecommunications system. In this case, the destination code numbers were combined manually which, owing to the wide range of destination code numbers and the possible effects of an incorrect configuration, represented an extensive and time-consuming task. Optimum combination with a minimum number of destination code numbers that nevertheless allowed least cost routing was achieved only rarely. In some cases, such combinations were even deliberately avoided, since this was detrimental to the clarity of the range of telephone numbers and the telephone number database, and costly manual changes would have been required if the area codes were subsequently changed. In Germany, for example, the range of available area codes changes roughly every 6 months.
It is accordingly an object of the invention to provide a method for compression of a telephone number database in a telecommunications system and a corresponding telecommunications systems that overcome the above-mentioned disadvantages of the prior art methods and devices of this general type, in which case the telephone number database, which contains the dialing patterns with specific destination code numbers (area codes), can be compressed, that is to say minimized, in as simple a manner as possible, with least cost routing determination also being possible. In particular, the method according to the invention is intended to allow the compression of the telephone number database to be automated.
The range of telephone numbers and the telephone number database in a telecommunications system include a plurality of data records, with each data record having a specific dialing pattern. Each dialing pattern or data record can be assigned specific attributes, which can be evaluated in order to control the individual dialing patterns or data records and, in particular, to determine the lowest cost connecting path.
According to a first exemplary embodiment of the present invention, a check is carried out to determine whether the dialing pattern of a first data record is covered by a more general and shorter dialing pattern of a second data record. This is predicated on the more general and shorter dialing pattern having the same attributes as the first-mentioned dialing pattern. If a corresponding more general and shorter dialing pattern has been found, the first-mentioned dialing pattern and the corresponding data record can be deleted.
According to a second exemplary embodiment of the present invention, a check is carried out to determine whether a plurality of dialing patterns are stored which have a matching or identical initial character sequence, that is to say a matching prefix, as well as identical attributes. If this is true, the dialing patterns determined in this way can be combined to form a more general and shorter dialing pattern. That is to say a range of dialing patterns is replaced by a complementary dialing pattern that simultaneously covers all the dialing patterns in the previously quoted range.
According to a third exemplary embodiment of the present invention, general dialing patterns which are in principle superfluous, since all the more specific dialing patterns which are covered by the general dialing pattern have already been separately identified, are deleted and eliminated.
The methods proposed according to the present invention for compression of the range of telephone numbers in telecommunications systems allow the process of minimizing the destination code numbers (area codes) to be automated. The compression method according to the present invention is preferably always carried out whenever the telecommunications system is being configured and is being prepared for use. The application of the present invention ensures that the number of destination code numbers and corresponding data records which can be used for least cost routing is always a minimum, so that the memory required for these data records in the respective telecommunications system can likewise be minimized. The minimum number of destination code numbers and data records to be controlled also results in a reduction in the time required to set up a call. The telephone number database can be configured quickly, reliably and correctly and, in particular, changes and adaptations to the telephone number database can be carried out without any problems owing to the small amount of effort involved.
In practice, the methods proposed according to the present invention can be combined with one another, that is to say carried out successively, with the individual methods being used, in particular, repeatedly until no further minimizing or compression of the telephone number database can be achieved.
With the foregoing and other objects in view there is provided, in accordance with the invention, a telecommunications system, including: a memory for storing a telephone number database having a plurality of data records each with a specific dialing pattern, the specific dialing pattern having a specific destination code number of a telecommunications network and assigned at least one specific attribute for controlling the specific dialing pattern; and a compression device for compression of the telephone number database stored in the memory and for performing the methods steps of the first embodiment, the second embodiment, the third embodiment or a combination of any or all of the embodiments.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a method for compression of a telephone number database in a telecommunications system, and a corresponding telecommunications system, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.